Unnamed Western intelligence officials assert that Iran helped the Palestinian militant group Hamas develop weapons used to strike Israel. The officials believe that Hamas commanders routinely traveled to Iran to receive training in the production and operation of weapons and to tour the Islamic Revolutionary Guard Corps' (IRGC's) own rocket-production facilities. According to the intelligence officials, Iran has also provided Hamas with technical advice for building weapon-production facilities in the Gaza Strip. One official said that Iranian support, which increased after Hamas' 2014 war with Israel, has led to "significant improvements in terms of range, precision, and the extent of destruction" of Hamas' weapons. Israeli defense officials have also concluded that Hamas' medium-range M-75 and J-80 rockets, while manufactured in Gaza, are based on Iranian designs.